What is black mold? Often, people ask what is black mold. Black mold is not a name of a specific type of mold. The name can apply to any type of mold that appears black. In indoor environment several types of mold can appear black. These include Cladosporium, Ulocladium, Aspergillus niger, and Stachybotrys. Some people tend to use the term black mold when they refer to Stachybotrys.